Rotary chamber-type compressor

ABSTRACT

A motor-compressor assembly of the accessible hermetic type has a substantially cylindrical casing containing an axial shaft which is direct-driven by an internal electric motor. The motor is located at one end of the assembly and the shaft projects through one or more rotary chamber-type compressor sections each having a stationary body defining a chamber contaianing a rotor which is driven by the shaft. Stationary plates at each end of each compressor body conduct the fluid to and from the compressing means and an unloading mechanism is shown carried thereby for varying the output of the compressor. The casing structure is shown as formed by a stacked and bolted assembly of a plurality of bodies and divider plates attached to a motor housing. The induction system embodies large volume, hollowed interiors of the rotors and large volume suction gas chambers in the divider plates to transfer suction fluid to the chambers at high volumetric flow rates with low pressure drop.

United States Patent King Inventor:

Assignee:

Filed:

Related US. Application Data Continuation-impart of Ser. No. 193,651, Oct. 29,

1971 abandoned.

US. Cl. 417/410; 418/60; 418/61 A;

Int. Cl. F04b 17/00; F04c 23/00 Field of Search 418/60, 61, 185, 212, 219,

References Cited UNITED STATES PATENTS Teves 418/60 Prendergast i. 418/212 X Zimmermann 123/845 X Ounsted 418/61 R X Bellmer 417/371 X Keylwert..... 418/60 X Cotton 418/61 A X Cheney 417/286 FOREIGN PATENTS OR APPLlCATlONS United Kingdom 418/61 A :m 1 It 3T"? T5? i 1/ 451 May 13, 1975 Primary Examiner-C. .1. Husar Assistant Examiner-Leonard Smith Attorney, Agent, or Firm-Harness, Dickey & Pierce [57] ABSTRACT A motor-compressor assembly of the accessible hermetic type has a substantially cylindrical casing containing an axial shaft which is direct-driven by an internal electric motor. The motor is located at one end of the assembly and the shaft projects through one or more rotary chamber-type compressor sections each having a stationary body defining a chamber contaianing a rotor which is driven by the shaft. Stationary plates at each end of each compressor body conduct the fluid to and from the compressing means and an unloading mechanism is shown carried thereby for varying the output of the compressor. The casing structure is shown as formed by a stacked and bolted assembly of a plurality of bodies and divider plates attached to a motor housing. The induction system embodies large volume, hollowed interiors of the rotors and large volume suction gas chambers in the divider plates to transfer suction fluid to the chambers at high volumetric flow rates with low pressure drop.

29 Claims, 17 Drawing Figures PATENTEB HAY I 31975 SflEEI 01 OF 10 PATENTED HAY I 3|975 PHENTED HAY I 3i975 SHEET 0 4 [if 10 PATENTED MAY 1 319. 5 3.883.273

sum cs or 10 FATENTEG W I 3 E75 SHEU U7UF 10 PATENTED HAY I 31975 SHEET CBUF 1O PATENTEQ MY] 31975 SHEET OSBF 1O PATENTED MAY 1 31975 SHET 1081 10 ROTARY CHAMBER-TYPE COMPRESSOR CROSS-REFERENCE TO RELATED APPLICATION This is a continuation-in-part of copening application Ser. No. l93.65l, filed Oct. 29, l97l, now abandoned.

BACKGROUND OF THE INVENTION A known type of rotary compressor has a stationary cavity of epitrochoidal profile containing a rotor to which an orbital and rotary movement is imparted by means of an eccentric and gearing, in such manner that lobes on the rotor trace the internal periphery of the cavity while chambers of changing volume are formed and rotate within the cavity. The overall objective of the present invention is to provide a compressor of the indicated type, which incorporates imporved valving and fluid handling arrangements and which may include a plurality of sections adapted to be operated either singly or in desired multiples. A further object is to provide such a compressor which is compact, rugged, which utilizes many duplicated parts of relatively low cost, and which is relatively simple to assemble and disassemble. Another object of the invention is to provide such a compressor incorporating parts which can be used in compressors of different total capacities, thereby minimizing the cost of tooling and manufacture where it is desired to produce several different sizes of compressors. A further object is to provide such a compressor the output of which is variable in a reliable and economical manner without substantial loss of efficiency. Further, known rotary mechanisms of the type discussed above, because, at least in part, of inherent structural details which provide a compact assembly, present problems with respect to the supply of suction gas to the chambers and complicated suction and discharge valve arrangements have been proposed to improve the efficiency of induction, Accordingly, still another object of the invention is to provide an induction system supplying suction fluid at high volumetric flow rates with low pressure drops.

Other objects and advantages will become apparent upon consideration of the present disclosure in its entirety.

BRIEF DESCRIPTION OF THE FIGURES OF DRAWING FIG. 1 is a longitudinal central vertical sectional view of a multiple unit motor-compressor incorporating the invention, taken on the plane designated by the line and arrows l-l of FIG. 2;

FIGS. 2-8 inclusive are sectional elevational views taken respectively and sequentially on the lines l1-l l to VIII-V111 of FIG. 1, looking in the directions of the arrows;

FIG. 9 is a view corresponding to a left end elevation of FIG. 1;

FIG. 10 is a detailed elevational view taken as indicated by the line and arrows XX on FIG. 3;

FIG. 11 is a view similar to FIG. 4, showing a modifled construction;

FIG. 12 is a cross-sectional view of the modified construction, corresponding to FIG. 5, showing different positions of the piston;

FIG. 13 is a cross-sectional view taken substantially on the line llllll, looking in the opposite direction from FIG. 3, and partly broken away; and

FIGS. 14 and 15 are sectional details taken respectively on the lines XIV-XIV and XV-XV of FIG. 11 and looking in the direction of the arrows.

FIG. 16 is cross-sectional view taken substantially on the line XVlX\/I of FIG. 3', and

FIG. 17 is a view similar to FIG. 4, showing another modified construction.

DETAILED DESCRIPTION OF PREFERRED FORMS OF THE INVENTION Referring now to the drawing, reference character 20 designates generally a cylindrical body section which constitutes the main housing for the electric motor of my improved motor compressor unit. The body section 20 is of cylindrical form, having its axis horizontal, and is carried by a hollow base 22 which also serves as an oil sump, the parts 20, 22 supporting the entire assembly. The stator 24 of a squirrel cage induction motor is mounted in the body section 20. The armature 25 of the motor is fast on the axial shaft 26, which projects to the left (as viewed in FIG. I) from body section 20. The motor parts may be of conventional construction and will require no detailed description.

At the rear end of the motor, shown at the right in FIG. I, the body is closed by a cover bell 28 sealed to the body section 20, rotatably supporting the shaft in bearing 30, and having an inlet port 32 for gas to be compressed. Inlet gas is delivered to the interior of the body section 20 through a substantially semitoroidal screen 33, and passes axially therethrough and through and around the motor parts to the front end of the motor. In refrigeration service this arrangement permits the residual heat absorbing capacity of returning gas to assist in cooling the motor.

A partitioning wall 40 integral with the body section 20 at the other end demarcates the motor compartment from the compressor section of the assembly, the shaft 26 extending rotatably through a center bearing 42 in the partition wall, and outwardly therefrom through bearings 44, 46 and 48 to drive the compressor means shown at the left of the partition wall. In the construction shown, three compressor sections are employed, but it will be seen that the number of sections is readily subject to variation. In the illustrated triple unit construction, shaft 26 projects beyond bearing 44 and through bearing 46, 48. The bea rings 44, 46, 48 are located in a series of axially spaced chambered divider plates 50, 51, 52.

Interposed between the plate 50 and the wall of body section 20 is a cylinder body 55. Additional cylinder bodies, respectively designated 56 and 57, are interposed between divider plates and 51 and between the plates 5] and 52, respectively. The outer face of partitioning wall 40, and all of the divider plates and cylinder bodies have their axial ends flat and perpendicular to the axis of the shaft. They are held tightly to gether in aligned and sealed relation to one another and to the conforming outer face of partition 40 by lag screws 60 which retain the parts in this relation and retain also at the outer end of this stacked assembly a discharge cover 58 which closes the left end of the assembly. Suitable pilot dowels 62 maintain alignment of parts, and integrity of sealing is assured by suitable 0- rings as 63, 64.

Each ofthe cylinder bodies 55, 56, 57 contains a cavity 65, 66, 67, open at both axial ends and which is of an epitrochoidal profile having two lobes (FIGS. 3, 5

and 7). Each cavity contains a piston or rotor 71, 72, 73 of generally triangular shape. Many elements of the cylinder bodies. divider plates, pistons and other parts are alike, so that repeated descriptions of similar parts will not be required. Each corner of each piston carries an apex seal assembly 74 extending the full axial length of the piston. The pistons are so moved that, in accordance with known practice, the apex seals trace and remain in sealing engagement with the internal peripheral wall of their cavity. Suitable end seals as 79, 89 are provided on each axial end of each piston to provide sealing engagement with the aforementioned flat end walls of the divider plates and partition wall. The details of the sealing assemblies and the geometrical aspects of the profiles and piston movement form no part of the present invention per se, and can follow known practice. However, although it will be recognized that features of the invention as herein described are particularly adapted to the general class of such mechanical transducers wherein such lobed rotors or pistons have a compound orbital-rotational movement which creates rotational chambers of changing volume within the cavities of the cylinder bodies as the resultant of two circular components of differing angular velocities about parallel axes.

An eccentric, 75, 76, 77, each of which is keyed to the shaft 26 to rotate therewith, is journaled within each of the pistons 71, 72, 73. The eccentrics and their keys 81 are shorter axially than the pistons, and each piston has an internal toothed gear portion 80 which overhangs one axial end of the eccentric and meshes with and rolls upon a fixed sun gear 78 projecting from an adjacent fixed wall. The internal toothed gear 80 is integral with the hub portion 92 of the piston and is of substantially greater diameter than the sun gear 78, gear 80 being concentric with the axis of the piston, while the sun gear is concentric with the shaft. The sun gear for piston 71 is carried by a sleeve 82 (FIG. 1) fast in the wall 40 and surrounding shaft bearing 42.. The similar stationary sun gears 84, 85 for the pistons 72, 73 are secured in and project laterally from the divider plates 50, 51, respectively.

The hub portion 92 of each piston is relatively thin in a radial direction and is journaled on its eccentric (as 75) by means of an interposed bearing 94. The peripheral wall 95 of the piston is also relatively thin in a radial direction and is joined to hub section 92 by integral spokes 96 which are shorter in an axial direction than the cylinder space 65, so that all of the interspoke areas are in free fluid conductive intercommunication, defining a hollowed interior of the piston. Suction gas passes from the motor chamber 35 via ports 90, 91 in wall 40 (FIG. 2) into the space between the inner and outer piston walls 92, 95 of piston 71 and during the suction phase is drawn outwardly through paired intake valve ports 100, 101, 102 (FIG. 3) in the peripheral wall 95 of the piston. On such pair of ports is formed between each pair of apex seals 74, and each pair of intake ports is controlled by a thin metal read-type double intake valve assembly 104 secured in position on the piston by rivets 105 (FIGS. 3 and Such arrangement is exemplary of a number of check-type valve constructions.

With the piston 71 in the position shown in FIG. 3 and moving clockwise, and considering the cylinder cavity 65 as divided thereby into the three rotating chamber spaces 110, 111, 112, it will be seen that chamber space is nearly at its maximum volume and will shortly begin to reduce in size. The gase contained therein was drawn into the same through the inlet ports and valve assembly on the piston during the suction phase, during such continued rotation the gas will be compressed and discharged through the outlet port 113 in the cylinder. Gas in chamber space 112 is also being discharged through the opposite outlet port 114. The outlet ports 113, 114 in peripheral cavity wall 120, and their associated check-type discharge valves 115, are alike, so that description of one will suffice.

Discharge gas passing through each of the outlet ports 113, 114 enters one of the chambers 116 located in diametrically opposite positions in a peripheral portion of the cylinder 55 (FIG. 3). Chambers 116 in cylinder 55 are in free communication with adjoining chamber areas 117, 118 and each of the two groups of chamber areas 116, 117, 118 forms one set of discharge pas sage portions. As shown in FIG. 3 one arrangement for establishing intercommunication among each set of chamber areas 116, 117, 118 is by means 8 circumfer entially extending passageways 119 which are formed by recessing the faces of ribs 124 which separate the individual chamber areas 116, 117, 118. Circumferentially extending passageways 119 are thus similar to circumferentially extending passages 141, which are illustrated in FIG. 16 and described in detail hereinbelow. All of the areas 116, 117, 118 are open at their sides facing divider plate 50 and are in communication with registering chamber spaces 121, 122, 123 in the plate 50 (FIGS. 1 and 4). The spaces 121, 122, 123 of each set also intercommunicate through circumferentially extending passageways 119 and are open at both axial ends and communicate with corresponding registering chamber spaces in the successively stacked cylinders and plates 56, 51, 57, 52, and with discharge chamber 150 in discharge cover 58. The discharge passageway system thus comprises two axially extending, circumferentially spaced sets of discharge passageways; with reference to FIG. 3, one set of passageways is positioned generally in the 1 oclock 3 oclock region and the other set is positioned generally in the 7 oclock 9 oclock region.

In the illustrated construction the three pumping sections operate in parallel for maximum volumetric out put, as is desirable where extremely low temperatures are not required. They could of course equally well be used in a series-staged arrangement for low temperature service and/or wherever higher output pressures might be described.

The parallel input feeding of suction gas from the motor housing chamber 35 for cylinders 56 and 57 is effected through peripherally outspaced ports 129 (FIGS. 1 and 2) which extend through wall 40 and lead to peripherally arranged suction passages formed by aligned chambers as 139, formed in and open at the axial ends of the stacked cylinders 55, 56 and plates 50, 51, respectively. Suction or intake ports 129 and passages 139, 140 are arranged peripherally similarly to but isolated from the discharge chamber spaces 116-118, 121-123 etc. The suction passageway system of the compressor thus comprises two axially extending, circumferentially spaced sets of suction passageways. As shown in FIG. 4, one set of suction passageways (chambers 140 in plate 50) is located generally at the 9 oclock 12 o'clock position, and the other set of suction passageways (chamber 140) is located generally in the 3 oclock -6 o'clock position. lntercommunication between the individual chambers of each set is established by circumferentially extending passageways 141 formed by recessing the axial ends of the radial ribs 125 which define the individual chambers 139, 140. The sets of suction passageways are isolated from the sets of discharge passageways by interventing radial ribs as 130 (FIGS. 1 and 4) which terminate in the planes of contact between the cylinder bodies 55, 56, and 57, the divider plates 50, 51 and 52, and the partitioning wall 40.

Gas for the second cylinder 56 is drawn from the 9 o'clock to 12 oclock set of passage spaces 140 in the divider plate 50 via an unloader valve assembly 127 (FIG. 4) carried by the divider plate. The unloader valve assembly controls the flow of gas through radially inwardly extending passage 132 leading to the large central chamber 170 in the divider plate. Ports 133 and 134 which open axially in the face of plate 50 on its surface toward cylinder 56, in the area between the inner and outer peripheral walls of piston 72, feed the suction gas from chamber 170 to the second pumping assembly in cylinder 56 in a manner corresponding to the functioning of the ports 90, 91 in the wall 40 which supply the first cylinder 55.

The operation of the unloading mechanism preferably conforms to the teaching of Cheney US. Pat. No. 3,578,883. A valve 126 is movable to close or open the passage 132 leading to the chamber 170, and so to inlet ports 133 and 134 to the hollowed interior of the rotor. Valve element 126 is powered by discharge gas pressure delivered via passage 137 and a solenoid-operated valve 135 from passage 121 to a chamber 136 which constitutes an actuating cylinder for the piston-type unloader valve 126 which, when closed by discharge pressure, interrupts the supply of fluid to the inlet of the second compressor section within body 56. More specifically, the valve element 126, normally biased to an open position by a spring 128, includes a piston portion slidable in chamber 136 and is moved to closed position shown in FIG. 4 by admission of high-pressure discharge gas to chamber 136. Discharge gas is passed into chamber 136 from discharge gas chamber space 121 sequentially through passageway 137, passageway 142, orifice 143, valve chamber 144 and passageway 145. The valve 135 is moved to open or close the orifice 143 by solenoid 146. When the solenoid is energized, the valve 135 is held in the position shown and the orifice 143 is open, and when the solenoid is deepergized, spring 147 moves the valve 135 to the right as viewed in the drawing so that valve ball 148 closes the orifice 143. When the orifice 143 is closed, discharge gas pressure in the chamber 136 is released and the chamber 136 communicates with relatively low pressure suction passage portion 140. Such communication is established through passageway 149, passageway 156, chamber 157, orifice 158 (around the stem of valve 135), valve chamber 144 and passageway 145. The suction gas pressure in chamber 136 is insufficient to overcome the force of spring 128 and the valve element 126 is moved to open position by action of spring 128 to establish communication between suction passage portion 140 and chamber 170 in divider 50. When the solenoid is energized to open orifice 143, the valve 135 moves so that valve ball 148 closes orifice 158. Thus, the chamber 136 is subjected to discharge pressure or suction pressure under control of the solenoid.

The similar operation and arrangement of the compressor sections contained in cylinders 56 and 57, and the unloader assembly 138 (FIG. 6) for cylinder 57, carried by divider plate 51, will not require detailed description. Gas is supplied to the third cylinder 57 from the set of suction gas passageways located in the hollow interior of divider plate 51 at the 3 o'clock 6 o'clock region via unloader valve assembly 138. This action is similar to the operation described hereinabove with respect to the supply of suction gas to the hollow interior of divider 50 and the unloader valve 138 functions in a manner similar to the unloader valve 127, to selectively control the supply of suction gas to the interior of divider 51. The output of both cylinders 56, 57 is delivered in similar fashion (when the unloader valves are open) to both sets of axially extending discharge passage spaces leading to chamber 150. It will be seen that by selective operation of the unloaders 127 and 138 the output of one, two or all three cylinders is available.

Divider plate 52 contains through passage spaces 121', 122', 123' (FIGS. land 8) which form continuations of and conduct discharge gas from passage spaces 116, 117, 118, 121, 122, 123 to the annular discharge chamber 150 in the discharge cover 58, but divider plate 52 is blanked off in the areas corresponding to the suction passage spaces 139, 140. Chamber 150 is isolated from the lower pressure area at the outer end of the shaft by a cylindrical wall 151, the space within which forms a chamber 154 for the end of the shaft and the counterweight 152. An equalizing passage 155 in plate 52 connects chamber 154 to the suction area 139 within the cylinder 57 and permits any oil leakage past bearing 48 to escape and return to oil sump 23 via valve 164.

The eccentrics and pistons are peripherally equian gularly spaced about the axis of rotation for balance of inertial forces and gas pulsations, which is of course an advantage of the multicylinder construction. The fact that the pistons travel at reduced speed, and other known characteristics. impart a smoothness of opera tion substantially greater than that obtainable with a reciprocatory piston machine of comparable capacity even where only a single pumping unit is employed. The counterweights 152, 153 at opposite ends of the compressor assembly offset the rotating couple effect resulting from the inertial forces from the three rotors and eccentrics.

In order to supply lubricant to the axial oil passage in shaft 26 for distribution therefrom to the bearings via suitable radial feed branches (undesignated), oil from sump 23 in base 22 is conducted via a riser passage 161 to the space between gears 78, 80. Gears 78, 80 function as a pump and are constructed and arranged for this purpose in the manner disclosed in U.S. Pat. No. 3,583,371, granted to me on June 8, 1971. Excess oil from the open (right hand) end of the shaft, as shown in FIG. 1, is returned to the sump through an opening 162 in screen retainer 34 and thence from the bottom of motor compartment 35 through the antifoaming check valve 164 which is normally open but closable by increased relative pressure in the sump. A construction of this type is disclosed in the US. Pat. to Neubauer, No. 3,123,287.

FIGS. 11-15 show a modified construction wherein no intake valves are required. Parts which correspond to those of the embodiment already described are designated by like reference characters distinguished by the addition of the letter A. and many of these will not require redescription.

In this embodiment ports (not shown) corresponding to ports 90, 91 {FIG 2) are formed in the partitioning wall. as 40 between the motor compartment and first cylinder. and similar ports, 133A, [34A, (FIGS. 11 and I4) corresponding to the ports I33, I34 of the first embodiment. are provided in the farther or left hand walls of the hollow divider members 50 and 51 (as viewed in FIG. I]. to deliver suction gas to the interiors of the pis tons 72 and 73. No valves are provided in the peripheral wall of the piston, however. and the suction gas is conducted from the hollow interior of the piston to the suction chamber areas of the cylinder via bridging or transfer ports I65, I66 FIGS. 12 and I3) formed as pockets in the right hand walls of the divider plates as viewed in FIG. 1. Each such transfer port is isolated from the hollow interior of the divider member by a wall 167 (FIG. 15) and each such pocketed port defines a gas passage through which suction gas is conducted from the interior of the piston contained in the cylinder located on the right of the divider member, as the parts are viewed in FIG. I, to the suction chamber space outside the peripheral wall of the piston. Suction gas for the second cylinder 56A of the modified construction (FlG. I2) is conducted to the interior of the piston of cylinder 56A via the ports 133A, 134A in the divider wall 150A shown in FIG. II, but the supply fo gas from the interior of the piston 72A in cylinder 56A to the suction spaces in cylinder 56A is conducted to such suction spaces through a pair of pocketed transfer ports (not shown) in the subsequent divider wall, corresponding to the divider wall 51 of the first embodiment. The relative position of the transfer ports 165, I66 is shown in FIG. 12, although of course the ports 165, 166 shown in dotted lines in FIG. 12 are the ones for the first cylinder, corresponding to cylinder 55 of the first embodiment. Similar pocketed bridging ports are provided in the final divider wall, corresponding to the divider wall 52 ofthe first embodiment, for feeding suction gas to the suction space of the final cylinder, where three cylinders are employed, although one or any number of cylinders may be used, as indicated. As brought out in FlG. 12, wherein one of the suction spaces is designated 116A, the transfer ports are so lo cated as to provide cross communication in a generally radial direction between the internal piston space and the suction chamber areas while the piston is moving in such regions as to define the expanding suction cham ber phases.

With this arrangement no requirement exists for valves in or gas flow through the peripheral wall of the piston. As also shown in FIG. 11, an unloader assembly 127A may be employed to control the admission of suction gas to the chamber 170A in the divider plate.

A modified construction for supplying suction gas to the cylinders is shown in FIG. 17. Parts in FIG. 17 which correspond to those of the embodiments already described are designated by like reference characters distinguishable by the addition of the letter B. In the embodiment of FIG. 17 both of the two axially extending sets of suction gas passageways feed suction gas to both of the dividers 5t) and 51. Thus, for example, in FIG. 17 chamber 1708 in hollow divider 50B is fed from the 9 oclock 12 o'clock set of suction gas passageways through the opening 1328 and also from the 3 oclock 6 oclock set of suction passageways through the opening 182. The space within the divider 51 would be fed with suction gas in a similar manner from both the 3 o'clock 6 oclock and the 9 oclock 12 oclock sets of passageways.

Unloader valves 1278 and 180 may be employed to selectively control the flow of suction gas to the chambers of dividers. As shown in FIG. 17 unloader valve 1278 may be used to control the flow of suction gas to the chamber 1708 of the divider 50B and unloader valve 180, of similar construction, may be provided to control the flow of suction through opening I82 to the chamber 1708. A pair of unloader valves may also be provided on the divider 51 to control the flow of suction gas through a pair of passages to the space within that divider. The pair of unloader valves on each divider may be selectively operated to modulate the output of the cylinder associated with that divider. Also, in a multi-cylinder device the output of one, two or more cylinders may be obtained.

All of the above-described embodiments of FIGS. I17 inclusive employ induction systems sharing common concepts which effect supply of suction gas to the rotating chambers at high volumetric flow rates and with low pressure drops and as a result, increase the efficiency of the compressor. More specifically, the ho]- lowed interior of each rotor provides a large volume of suction gas which is in close proximity to and in continuous communication with the valve means which sup ply suction gas to the rotating chambers. Hence, upon the opening of any valve means upon a rotating chamber entering the suction phase, which action occurs at spaced time intervals, the entire large volume of suction gas in the hollowed rotor is available to supply the chamber with suction gas at high volumetric flow rates for rapid charging. The valve means can be in the form of pressure-responsive valves in the peripheral wall of the rotor, as in the embodiment of FIGS. 1-10, or in the form of slide valves such as are formed by transfer ports in a cylinder end wall and opened and closed by the rotor, as in the embodiment in FIGS. lll5. It will be appreciated that additional transfer ports could be formed in the other end wall of the cavity for increased flow rate into the chamber. In both embodiments, the valve means is in continuous communication with the large volume of suction gas within the hollowed interior of the rotor and the only pressure drop upon flow of suction gas to the chamber resides in the flow of suction gas through the valve means which may be designed to provide maximum flow rates.

The hollowed interior of each rotor is in continuous communication with suction gas ports or passageways which supply suction gas to the hollowed interior of the rotor and such ports or passageways are in continuous fluid communication with a reservoir of suction gas of large volume located in contiguous relation with the rotor. This arrangement permits the continuous flow of suction gas to the hollowed interior of the rotor with low energy loss and further improves the efficiency of the induction system. In the multiple-rotor embodiment of FIG. I, the large reservoir of suction gas which feeds the hollow interior of the first rotor 71 comprises the chamber defined by the motor compartment 35, while the hollowed interior of the rotors 76 and 77 are respectively fed with suction gas from the reservoirs provided by the dividers 50 and 51 such as the space of divider 50. As seen from FIGS. 2, 4, ll, 12 and 17 ports or passageways that feed suction gas to the hollowed interior of the rotors are in continuous communication with the hollowed interior of the rotors irrespective of the angular position of the rotors. In this regard it will be appreciated that the showing in FIGS. 4 and 11 of the peripheral wall of rotors 71 and 71A in broken lines differ from the position of rotor 71 in FIG. 1 to illustrate the foregoing relationship. In a singlecylinder embodiment in which with reference to FIG. 1, all components between cylinder 55 and divider 52 are removed and the divider plate 52 is placed directly against cylinder 55 along the section line 1111 1 l, the reservoir providing a large volume of suction gas which supplies suction gas continuously to the hollowed interior of rotor 71 is defined by the motor compartment. In single rotor arrangements not employing a motor compartment, a hollowed structure providing a large volume of suction gas in contiguous relation with the rotor and in continuous communication with the hollowed interior of the rotor, such as a hollowed structure similar to dividers 50 and 51, may be provided.

The volume of the hollowed interior of the rotor should have a relationship with the maximum volume of each rotating chamber so that the volume of gas entering and leaving the hollowed interior of the rotor permits the flow of suction gas to the hollowed interior of the rotor with maximum volumetric flow rate and with minimum pressure drop. Preferably, the volume of the hollowed interior of the rotor should be at least about equal to the maximum volume of each rotating chamber. The efficiency of the induction system is further improved by providing a reservoir of suction gas, from which suction gas is supplied to the hollowed interior of the rotor, also of a volume at least about equal to the maximum volume of each rotating chamber. Fluid communication between the reservoir and the hollowed interior of the rotor is further improved by ports sized to provide minimum pressure drop of the suction gas flow from the reservoir to the hollowed interior of the rotor for all suction gas flow conditions during operation of the compressor. A single rotor compressor, having a rotor and a cylinder similar to rotor 71 and cylinder 55 shown in FIG. 1, has been con structed to provide a total displacement of l7.2 cubic inches (8.6 cubic inches for each chamber). In such [72 cubic inch compressor it was found possible to structurally design the rotor to possess a hollowed interior of 1 L cubic inches without increasing the size of the rotor and outer periphery of the cylinder beyond that required to obtain the design displacement of 17.2 cubic inches. Also, the area of the hollowed rotor lying in a plane perpendicular to the axis of rotation of the rotor permitted the use of ports feeding suction gas to the hollow interior of the rotor of total cross section area such as to permit the flow of suction gas to the hoilow interior of the rotor with minimum pressure drop, for all suction gas flow conditions.

While in the embodiments illustrated the cylinder profiles are described as being of epitrochoidal shape, it is to be understood that other profiles, such as modified epitrochoids, parametric curves of epitrochoids, and curves of oval shape, can be used.

This Detailed Description of Preferred Forms of the Invention, and the accompanying drawings, have been furnished in compliance with the statutory requirement to set forth the best mode contemplated by the inventor of carrying out the invention. The prior portions consisting of the Abstract of the Disclosure and the Background of the Invention are furnished without the prejudice to comply with administrative requirements of the Patent Office.

What is claimed is:

1. In a rotating chamber-type pumping device including a body structure having a cavity therein and having an end wall, a rotor in the cavity having a compound movement which is the resultant of two circular components of rotation about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor. 21 fluid inlet orifice in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a checktype outlet valve controlling flow through said outlet port, a shaft for driving said rotor, said end wall extending radially outwardly a substantial distance beyond said orifice, a second pumping device located on the opposite side of the body from said end wall and also drivable by said shaft; the improvement comprising the rotor being hollow and said inlet orifice extending through said end wall within the peripheral path of and discharging into the interior of the rotor of the firstmentioned pumping device, an additional inlet orifice extending through said body structure radially outwardly of said cavity, a chambered divider member be tween the first and second pumping devices having passage portions therein communicating with said addi tional inlet orifice and with said second pumping device to supply fluid to the latter, and a transfer port in said divider member segregated from said passage portions and openings into the cavity of said first mentioned pumping device at positions both inwardly and out wardly of the peripheral wall of the rotor, on the side of the rotor opposite said end wall, to transfer fluid from the hollow interior of the rotor to a suction area of the cavity outside the periphery of the rotor.

2. Rotating chamber-type pumping apparatus com' prising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a rotor in the cav ity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotation about parallel axes a different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, and outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a checktype outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite from the motor housing portion and also drivable by said shaft, the rotor being hollowed and the first-mentioned fluid inlet orifice extending through said end wall within the peripheral path of and discharging into the interior of the rotor of the firstmentioned pumping device, a divider member interposed between said two pumping devices on the opposite side of said first-mentioned pumping device from said end wall, said divider member having a relatively large chamber therein, additional inlet passage means interconnecting the interior of the motor housing portion with the last-mentioned chamber independently of the aforementioned fluid inlet orifice, inlet port portions in said divider member for connecting said cham her to the second pumping device, and a radially extending transfer port in said divider member segregated from said chamber and open on its side facing the cavity of the first-mentioned pumping device at positions both inwardly and outwardly of the peripheral wall of the rotor, to transfer fluid from the hollow interior of the rotor of the first'mentioned pumping device to a suction area of the cavity outside the periphery of the rotor thereof.

3. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotation about parallel axis at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, and outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite from the motor housing portion and also drivable by said shaft, the rotor being hollowed and the first-mentioned fluid inlet orifice extending through said end wall within the peripheral path of and dis charging into the interior of the rotor of the firstmentioned pumping device, a divider member interposed between said two pumping devices on the opposite side of said first-mentioned pumping device from said end wall, said divider member having a relatively large chamber therein and means defining an opposite end wall of the cavity of the first-mentioned pumping device, additional inlet passage means interconnecting the interior of the motor housing portion with the lastmentioned chamber independently of the aforementioned fluid inlet orifice, inlet port portions in said divider member for connecting said chamber to the second pumping device, and a radially extending transfer port in one of said end walls of the cavity of the firstmentioned pumping device open at position both inwardly and outwardly of the peripheral wall of the rotor, to transfer fluid from the hollow interior of the rotor of the first-mentioned pumping device of a suc' tion area of the cavity outside the periphery of the rotor thereof.

4. In a rotating-chamber type gas compressor, the combination of: two body structures aligned in spaced apart relationship along the axis of rotation of the compressor, said bodies having inner peripheral walls defining first and second cylindrical cavities respectively around said axis; a divider plate having opposed end walls disposed between and connected to said body structures, each divider plate end wall defining a first end wall of a respective one of said cavities, said divider plate having a suction gas chamber therein; closure means defining a second end wall of each said cavity; first and second flow multi-lobed rotors in said first and second cavities respectively, each said rotor having peripheral walls between the lobes thereof; means for mounting each hollow rotor for rotation in its respective cavity with a compound orbital-rotational movement about said axis with the lobes of each rotor in sealing engagement with peripheral wall of its respective cavity to form plural rotating chambers of changing volume lying radially outside the peripheral walls of the rotor; first port means in said second end wall of said first cavity for feeding suction gas to the hollow interior of said first rotor in all positions thereof; second port means in said first end wall of said second cavity for feeding suction gas from said suction gas chamber to the hollow interior of said second rotor in all positions thereof, said first end wall of said first cavity preventing communication of suction gas from said suction gas chamber to said first rotor; inlet means placing the hollow interior of each rotor in fluid communica tion with its respective rotating chambers to feed suction gas from the interior of the rotor to said rotating chambers; inlet passage means for communicating suction gas to said suction gas chamber; and outlet passage means in communication with each cavity.

5. In a rotating-chamber type gas compressor, the combination of: two body structures aligned in spaced apart relationship along the axis of rotation of the compressor, said bodies having inner peripheral walls defining first and second cylindrical cavities respectively around said axis; a divider plate having opposed end walls disposed between and connected to said body structures, each divider plate end wall defining a first end wall ofa respective one of said cavities, said divider plate having a suction gas chamber therein; closure means defining a second end wall of each said cavity; first and second hollow multi-lobed rotors in said first and second cavities respectively, each said rotor having peripheral walls between the lobes thereof; means for mounting each hollow rotor for rotation in its respective cavity with a compound orbital-rotational move ment about said axis with the lobes of each rotor in sealing engagement with the peripheral wall of its respective cavity to form plural rotating chambers of changing volume lying radially outside the peripheral walls of the rotor; first port means in said second end wall of said first cavity for feeding suction gas to the hollow interior of said first rotor in all positions thereof; second port means in said first end wall of said second cavity for feeding suction gas from said suction gas chamber to the hollow interior of said second rotor in all positions thereof; means defining a transfer port in said first end wall of said first cavity for placing the hollow interior of said first rotor in fluid communication with the rotating chambers created thereby, said transfer port being fromed by wall means preventing communication of suction gas from said suction gas chamber to said first rotor; inlet means placing the hollow interior of said second rotor in communication with the rotating chambers created thereby; inlet passage means for communicating suction gas to said suction gas chamber; and outlet passage means in communication with each cavity.

6. A divider plate for a rotating-chamber type fluidhandling rotary piston machine having at least two cavities each with a generally hollow rotor disposed therein mounted for orbital-rotational movement with respect thereto, said divider plate being disposed between the cavities and comprising: side walls having opposed outer end surfaces and inner and outer periph eral walls disposed between said side walls defining a generally hollow interior, said hollow interior being generally annular and circumscribing the axis of rotation of the rotors, each said end surface forming an end wall ofone of the cavities; inlet means for communicating inlet fluid to said hollow interior of said divider plate; means defining a passageway through one said end surface for communicating fluid from said hollow interior to one said cavity; and means defining a trans' fer port in the other said end surface for placing the hollow interior of the rotor in the other said cavity in fluid communication with the exterior of such rotor, said transfer port being formed by wall means prevent ing direct communication between fluid in said transfer port and fluid in said hollow interior of said divider plate.

7. A divider plate as claimed in claim 6, wherein said machine has a shaft interconnecting said rotors, and further comprising bearing means disposed within said inner peripheral wall for rotatably journaling said shaft.

8. A fluid-handling piston machine comprising: an annular body having an inner peripheral surface defining the peripheral wall of a cylindrical cavity extending around the axis of the machine; a plate structure connected to said body and having at one end a surface defining one end wall of said cavity, said plate structure having an induction chamber therein; means defining an opposite end wall of said cavity; a piston mounted in said cavity for movement with respect to said body in a plane transverse to said axis, said piston having an outer periheral surface facing said inner peripheral surface of said body and end surfaces in sealing engagement with the end walls of said cavity, said piston having a generally hollow interior open at said end surfaces thereof; means for controlling the relative movement of said piston with respect to its body so that such movement creates at least one working chamber of increasing and decreasing volume between said outer peripheral surface of said piston and said inner peripheral surface of said body, said induction chamber having a volume equal to or greater than the displacement of said working chamber; an inlet passageway for placing said induction chamber in fluid communication with the hollow interior of said piston in all positions thereof; inlet means for communicating inlet fluid to said induction chamber; passage means for placing said hollow interior of said piston in fluid communication with said working chamber created thereby at predetermined intervals; and outlet means for communicating outlet fluid from said cavity.

9. A machine as claimed in claim 8, wherein said induction chamber is generally annular in shape and circumscribes said axis.

10. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a hollowed rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotation about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in said end wall for supplying fluid to a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice ap purtenant to said end wall, said end wall comprising a partition extending radially outwardly beyond said orifice between the motor housing portion and said pump ing device, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite the motor housing portion and also drivable by said shaft, a divider member interposed between said two pumping devices on the opposite side of said firstmentioned pumping device from the partition, said divider member having a chamber therein, additional inlet passage means interconnecting the interior of the motor housing portion with the last-mentioned chamber independently of the aforementioned fluid inlet orifree, and inlet port portions in said divider member for said second pumping device.

11. In combination with the apparatus defined in claim 10, an unloader comprising a shutoff valve can ried by said divider member for controlling communicating between said additional inlet passage means and the inlet port portions for the second pumping device, and means powered by pressure derived from said outlet port for actuating said shutoff valve.

12. ln combination with the apparatus defined in claim 10, an unloader carried by said divider member for closing said additional inlet passage means to the second pumping device.

13. The apparatus defined in claim 12 wherein said unloader comprises a shutoff valve controlling commu nication between said additional inlet passage means and said inlet port portions for the second pumping device.

14. Rotating chamber-type pumping apparatus com prising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a hollowed rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the result of two circular components of rotation about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall ofthe rotor, a fluid inlet orifree for said pumping device in said end wall for supplying fluid to a suction chamber-defining area ofthe cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft. a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice up purtenant to said end wall, said end wall comprising a partition extending radially outwardly beyond said orifice between the motor housing portion and said pumping device, a main service inlet opening into the interior of said motor housing portion. the pumping apparatus being characterized by a second pumping device lo cated on the side of the first pumping device opposite the motor housing portion and also drivable by said shaft. an additional inlet orifice extending through said partition radially outwardly of said cavity, and inlet passage portions extending axially in said body struc ture and isolated from said cavity and providing communication between said additional inlet orifice and said second pumping device to supply fluid thereto.

15. In combination with the apparatus defined in claim 14, an unloader member for said second pumping device carried by said divider.

16. A pumping apparatus as defined in claim 14 wherein the first-mentioned fluid inlet orifice extends through said end wall within the peripheral path of and discharges into the interior of the rotor of the firstmentioned pumping device, and further comprising a chambered divider member between said first and second pumping devices having passage portions therein forming a part of said means communicating with the second pumping device to supply fluid thereto, and a transfer port in said divider member segregated from said passage portions and opening into the cavity of said first-mentioned pumping device at positions both inwardly and outwardly of the peripheral wall ofthe rotor, on the side of the rotor opposite said end wall, to transfer fluid from the hollow interior of the rotor to a suction area of the cavity outside the periphery of the rotor.

17. in combination with the apparatus defined in claim 14, a divider member interposed between said two pumping devices on the opposite side of the firstmentioned pumping device from said partition and containing a chamber and having further inlet passage portions interconnecting said previously mentioned inlet passage portions with said chamber and also hav ing an inlet port for the second pumping device leading from the chamber to said second pumping device.

18. A combination as defined in claim 17, wherein said second-mentioned pumping device includes a body portion having further inlet passage portions extending entirely therethrough in an axial direction and connected to previously mentioned inlet passage portions whereby a third pumping device may be arranged with its inlet in communication therewith on the opposite side of the second pumping device.

19. A combination as defined in claim 17, wherein said divider member contains a separate outlet passage portion isolated from the chamber and from the inlet passage portions and extending therethrough in an axial direction and communicating with said outlet port in the body structure.

20. A combination as defined in claim 19 wherein said second pumping device includes a second body portion having segregated passages extending entirely therethrough in an axial direction and communicating with said further inlet passage portions and with said outlet passage portions whereby additional pumping devices may be serially assembled beyond the second on said opposite side in operative communication with said further inlet passage portions and the outlets of all such pumping devices may be conducted to the end of such assembly farthest from the motor housing.

21. A rotatingchamber type gas compressor comprising: an annular body having an inner peripheral surface defining the peripheral wall of a cylindrical cavity extending around the axis of said compressor; a plate structure connected to said body and having at one end a surface defining one end wall of said cavity, said plate structure having an induction chamber therein; means defining an opposite end wall of said cavity; a piston mounted in said cavity for movement with respect to said body in plane transverse to said axis, said piston having an outer peripheral surface facing said inner peripheral surface of said body and opposite end surfaces in sealing engagement with the end walls of said cavity, said piston having a generally hollow interior open at both said end surfaces thereof; means for mounting said piston for compound orbital-rotational movement with respect to said body whereby at least one working chamber of increasing and decreasing volume is created between said outer peripheral surface of said piston and said inner peripheral surface of said body, said hollow interior of said piston having a volume equal to or greater than the displacement of said working chamber; and inlet passageway extending from said induc' tion chamber through said one end wall for placing said induction chamber in fluid communication with the hollow interior of said piston in all positions thereof; inlet means for communicating inlet fluid to said induction chamber; passage means spaced from said one end wall for placing said hollow interior of said piston in fluid communication with said working chamber created thereby at predetermined intervals; and outlet means for communicating outlet fluid from said cavity.

22. A gas compressor as claimed in claim 21, wherein said hollow interior of said piston entirely surrounds said axis.

23. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is epitrochoidal in crosssectional configuration.

24. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is parametric epitrochoidal in cross-sectional configuration.

25. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is oval in cross-sectional configuration.

26. A gas compressor as claimed in claim 21, wherein said passage means comprises a transfer port in one of said end walls of said cavity.

27. A gas compressor as claimed in claim 21, wherein said passage means comprises a port through said outer peripheral surface of said piston, and a check-type valve for controlling flow through said port.

28. A gas compressor as claimed in claim 21, wherein said piston comprises an annular outer peripheral wall portion, an inner annular hub portion, and generally radially extending spokes interconnecting said portions.

29. A gas compressor as claimed in claim 28, wherein said spokes are spaced inwardly from the planes of said opposite end surfaces of said piston. 

1. In a rotating chamber-type pumping device including a body structure having a cavity therein and having an end wall, a rotor in the cavity having a compound movement which is the resultant of two circular components of rotation about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, said end wall extending radially outwardly a substantial distance beyond said orifice, a second pumping device located on the opposite side of the body from said end wall and also drivable by said shaft; the improvement comprising the rotor being hollow and said inlet orifice extending through said end wall within the peripheral path of and discharging into the interior of the rotor of the first-mentioned pumping device, an additional inlet orifice extending through said body structure radially outwardly of said cavity, a chambered divider member between the first and second pumping devices having passage portions therein communicating with said additional inlet orifice and with said second pumping device to supply fluid to the latter, and a transfer port in said divider member segregated from said passage portions and openings into the cavity of said first mentioned pumping device at positions both inwardly and outwardly of the peripheral wall of the rotor, on the side of the rotor opposite said end wall, to transfer fluid from the hollow interior of the rotor to a suction area of the cavity outside the periphery of the rotor.
 2. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotation about parallel axes a different angular velocities whereby rotating chambers of chanGing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, and outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite from the motor housing portion and also drivable by said shaft, the rotor being hollowed and the first-mentioned fluid inlet orifice extending through said end wall within the peripheral path of and discharging into the interior of the rotor of the first-mentioned pumping device, a divider member interposed between said two pumping devices on the opposite side of said first-mentioned pumping device from said end wall, said divider member having a relatively large chamber therein, additional inlet passage means interconnecting the interior of the motor housing portion with the last-mentioned chamber independently of the aforementioned fluid inlet orifice, inlet port portions in said divider member for connecting said chamber to the second pumping device, and a radially extending transfer port in said divider member segregated from said chamber and open on its side facing the cavity of the first-mentioned pumping device at positions both inwardly and outwardly of the peripheral wall of the rotor, to transfer fluid from the hollow interior of the rotor of the first-mentioned pumping device to a suction area of the cavity outside the periphery of the rotor thereof.
 3. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotation about parallel axis at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in the end wall communicating with a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, and outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite from the motor housing portion and also drivable by said shaft, the rotor being hollowed and the first-mentioned fluid inlet orifice extending through said end wall within the peripheral path of and discharging into the interior of the rotor of the first-mentioned pumping device, a divider member interposed between said two pumping devices on the opposite side of said first-mentioned pumping device from said end wall, said divider member having a relatively large chamber therein and means defining an opposite end wall of the cavity of the first-mentioned pumping device, additional inlet pasSage means interconnecting the interior of the motor housing portion with the last-mentioned chamber independently of the aforementioned fluid inlet orifice, inlet port portions in said divider member for connecting said chamber to the second pumping device, and a radially extending transfer port in one of said end walls of the cavity of the first-mentioned pumping device open at position both inwardly and outwardly of the peripheral wall of the rotor, to transfer fluid from the hollow interior of the rotor of the first-mentioned pumping device of a suction area of the cavity outside the periphery of the rotor thereof.
 4. In a rotating-chamber type gas compressor, the combination of: two body structures aligned in spaced apart relationship along the axis of rotation of the compressor, said bodies having inner peripheral walls defining first and second cylindrical cavities respectively around said axis; a divider plate having opposed end walls disposed between and connected to said body structures, each divider plate end wall defining a first end wall of a respective one of said cavities, said divider plate having a suction gas chamber therein; closure means defining a second end wall of each said cavity; first and second flow multi-lobed rotors in said first and second cavities respectively, each said rotor having peripheral walls between the lobes thereof; means for mounting each hollow rotor for rotation in its respective cavity with a compound orbital-rotational movement about said axis with the lobes of each rotor in sealing engagement with peripheral wall of its respective cavity to form plural rotating chambers of changing volume lying radially outside the peripheral walls of the rotor; first port means in said second end wall of said first cavity for feeding suction gas to the hollow interior of said first rotor in all positions thereof; second port means in said first end wall of said second cavity for feeding suction gas from said suction gas chamber to the hollow interior of said second rotor in all positions thereof, said first end wall of said first cavity preventing communication of suction gas from said suction gas chamber to said first rotor; inlet means placing the hollow interior of each rotor in fluid communication with its respective rotating chambers to feed suction gas from the interior of the rotor to said rotating chambers; inlet passage means for communicating suction gas to said suction gas chamber; and outlet passage means in communication with each cavity.
 5. In a rotating-chamber type gas compressor, the combination of: two body structures aligned in spaced apart relationship along the axis of rotation of the compressor, said bodies having inner peripheral walls defining first and second cylindrical cavities respectively around said axis; a divider plate having opposed end walls disposed between and connected to said body structures, each divider plate end wall defining a first end wall of a respective one of said cavities, said divider plate having a suction gas chamber therein; closure means defining a second end wall of each said cavity; first and second hollow multi-lobed rotors in said first and second cavities respectively, each said rotor having peripheral walls between the lobes thereof; means for mounting each hollow rotor for rotation in its respective cavity with a compound orbital-rotational movement about said axis with the lobes of each rotor in sealing engagement with the peripheral wall of its respective cavity to form plural rotating chambers of changing volume lying radially outside the peripheral walls of the rotor; first port means in said second end wall of said first cavity for feeding suction gas to the hollow interior of said first rotor in all positions thereof; second port means in said first end wall of said second cavity for feeding suction gas from said suction gas chamber to the hollow interior of said second rotor in all positions thereof; means defining a transfer port in said first end wall of said first cavity for Placing the hollow interior of said first rotor in fluid communication with the rotating chambers created thereby, said transfer port being fromed by wall means preventing communication of suction gas from said suction gas chamber to said first rotor; inlet means placing the hollow interior of said second rotor in communication with the rotating chambers created thereby; inlet passage means for communicating suction gas to said suction gas chamber; and outlet passage means in communication with each cavity.
 6. A divider plate for a rotating-chamber type fluid-handling rotary piston machine having at least two cavities each with a generally hollow rotor disposed therein mounted for orbital-rotational movement with respect thereto, said divider plate being disposed between the cavities and comprising: side walls having opposed outer end surfaces and inner and outer peripheral walls disposed between said side walls defining a generally hollow interior, said hollow interior being generally annular and circumscribing the axis of rotation of the rotors, each said end surface forming an end wall of one of the cavities; inlet means for communicating inlet fluid to said hollow interior of said divider plate; means defining a passageway through one said end surface for communicating fluid from said hollow interior to one said cavity; and means defining a transfer port in the other said end surface for placing the hollow interior of the rotor in the other said cavity in fluid communication with the exterior of such rotor, said transfer port being formed by wall means preventing direct communication between fluid in said transfer port and fluid in said hollow interior of said divider plate.
 7. A divider plate as claimed in claim 6, wherein said machine has a shaft interconnecting said rotors, and further comprising bearing means disposed within said inner peripheral wall for rotatably journaling said shaft.
 8. A fluid-handling piston machine comprising: an annular body having an inner peripheral surface defining the peripheral wall of a cylindrical cavity extending around the axis of the machine; a plate structure connected to said body and having at one end a surface defining one end wall of said cavity, said plate structure having an induction chamber therein; means defining an opposite end wall of said cavity; a piston mounted in said cavity for movement with respect to said body in a plane transverse to said axis, said piston having an outer periheral surface facing said inner peripheral surface of said body and end surfaces in sealing engagement with the end walls of said cavity, said piston having a generally hollow interior open at said end surfaces thereof; means for controlling the relative movement of said piston with respect to its body so that such movement creates at least one working chamber of increasing and decreasing volume between said outer peripheral surface of said piston and said inner peripheral surface of said body, said induction chamber having a volume equal to or greater than the displacement of said working chamber; an inlet passageway for placing said induction chamber in fluid communication with the hollow interior of said piston in all positions thereof; inlet means for communicating inlet fluid to said induction chamber; passage means for placing said hollow interior of said piston in fluid communication with said working chamber created thereby at predetermined intervals; and outlet means for communicating outlet fluid from said cavity.
 9. A machine as claimed in claim 8, wherein said induction chamber is generally annular in shape and circumscribes said axis.
 10. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a hollowed rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the resultant of two circular components of rotatiOn about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in said end wall for supplying fluid to a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, said end wall comprising a partition extending radially outwardly beyond said orifice between the motor housing portion and said pumping device, and a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite the motor housing portion and also drivable by said shaft, a divider member interposed between said two pumping devices on the opposite side of said first-mentioned pumping device from the partition, said divider member having a chamber therein, additional inlet passage means interconnecting the interior of the motor housing portion with the last-mentioned chamber independently of the aforementioned fluid inlet orifice, and inlet port portions in said divider member for said second pumping device.
 11. In combination with the apparatus defined in claim 10, an unloader comprising a shutoff valve carried by said divider member for controlling communicating between said additional inlet passage means and the inlet port portions for the second pumping device, and means powered by pressure derived from said outlet port for actuating said shutoff valve.
 12. In combination with the apparatus defined in claim 10, an unloader carried by said divider member for closing said additional inlet passage means to the second pumping device.
 13. The apparatus defined in claim 12 wherein said unloader comprises a shutoff valve controlling communication between said additional inlet passage means and said inlet port portions for the second pumping device.
 14. Rotating chamber-type pumping apparatus comprising a body structure having a cavity therein for a first pumping device, said cavity having an end wall, said first pumping device comprising a hollowed rotor in the cavity having a peripheral wall, means mounting the rotor for rotation in the cavity with a compound movement which is the result of two circular components of rotation about parallel axes at different angular velocities whereby rotating chambers of changing volume are created in areas of the cavity lying radially outside the peripheral wall of the rotor, a fluid inlet orifice for said pumping device in said end wall for supplying fluid to a suction chamber-defining area of the cavity outside the peripheral wall of the rotor, an outlet port in the body structure communicating with the exterior and with a compression chamber-defining area of the cavity, a check-type outlet valve controlling flow through said outlet port, a shaft for driving said rotor, a motor for driving the shaft, a motor housing portion interiorly communicating with said fluid inlet orifice and in sealingly overengaged relation to said orifice appurtenant to said end wall, said end wall comprising a partition extending radially outwardly beyond said orifice between the motor housing portion and said pumping device, a main service inlet opening into the interior of said motor housing portion, the pumping apparatus being characterized by a second pumping device located on the side of the first pumping device opposite the motor housing portion and also drivable by said shaft, an additional inlet orifice extending through said partition radiAlly outwardly of said cavity, and inlet passage portions extending axially in said body structure and isolated from said cavity and providing communication between said additional inlet orifice and said second pumping device to supply fluid thereto.
 15. In combination with the apparatus defined in claim 14, an unloader member for said second pumping device carried by said divider.
 16. A pumping apparatus as defined in claim 14 wherein the first-mentioned fluid inlet orifice extends through said end wall within the peripheral path of and discharges into the interior of the rotor of the first-mentioned pumping device, and further comprising a chambered divider member between said first and second pumping devices having passage portions therein forming a part of said means communicating with the second pumping device to supply fluid thereto, and a transfer port in said divider member segregated from said passage portions and opening into the cavity of said first-mentioned pumping device at positions both inwardly and outwardly of the peripheral wall of the rotor, on the side of the rotor opposite said end wall, to transfer fluid from the hollow interior of the rotor to a suction area of the cavity outside the periphery of the rotor.
 17. In combination with the apparatus defined in claim 14, a divider member interposed between said two pumping devices on the opposite side of the first-mentioned pumping device from said partition and containing a chamber and having further inlet passage portions interconnecting said previously mentioned inlet passage portions with said chamber and also having an inlet port for the second pumping device leading from the chamber to said second pumping device.
 18. A combination as defined in claim 17, wherein said second-mentioned pumping device includes a body portion having further inlet passage portions extending entirely therethrough in an axial direction and connected to previously mentioned inlet passage portions whereby a third pumping device may be arranged with its inlet in communication therewith on the opposite side of the second pumping device.
 19. A combination as defined in claim 17, wherein said divider member contains a separate outlet passage portion isolated from the chamber and from the inlet passage portions and extending therethrough in an axial direction and communicating with said outlet port in the body structure.
 20. A combination as defined in claim 19 wherein said second pumping device includes a second body portion having segregated passages extending entirely therethrough in an axial direction and communicating with said further inlet passage portions and with said outlet passage portions whereby additional pumping devices may be serially assembled beyond the second on said opposite side in operative communication with said further inlet passage portions and the outlets of all such pumping devices may be conducted to the end of such assembly farthest from the motor housing.
 21. A rotating-chamber type gas compressor comprising: an annular body having an inner peripheral surface defining the peripheral wall of a cylindrical cavity extending around the axis of said compressor; a plate structure connected to said body and having at one end a surface defining one end wall of said cavity, said plate structure having an induction chamber therein; means defining an opposite end wall of said cavity; a piston mounted in said cavity for movement with respect to said body in plane transverse to said axis, said piston having an outer peripheral surface facing said inner peripheral surface of said body and opposite end surfaces in sealing engagement with the end walls of said cavity, said piston having a generally hollow interior open at both said end surfaces thereof; means for mounting said piston for compound orbital-rotational movement with respect to said body whereby at least one working chamber of increasing and decreasing volume is created between said outer peripheral surface of said piston and said innEr peripheral surface of said body, said hollow interior of said piston having a volume equal to or greater than the displacement of said working chamber; and inlet passageway extending from said induction chamber through said one end wall for placing said induction chamber in fluid communication with the hollow interior of said piston in all positions thereof; inlet means for communicating inlet fluid to said induction chamber; passage means spaced from said one end wall for placing said hollow interior of said piston in fluid communication with said working chamber created thereby at predetermined intervals; and outlet means for communicating outlet fluid from said cavity.
 22. A gas compressor as claimed in claim 21, wherein said hollow interior of said piston entirely surrounds said axis.
 23. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is epitrochoidal in cross-sectional configuration.
 24. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is parametric epitrochoidal in cross-sectional configuration.
 25. A gas compressor as claimed in claim 21, wherein said cylindrical cavity is oval in cross-sectional configuration.
 26. A gas compressor as claimed in claim 21, wherein said passage means comprises a transfer port in one of said end walls of said cavity.
 27. A gas compressor as claimed in claim 21, wherein said passage means comprises a port through said outer peripheral surface of said piston, and a check-type valve for controlling flow through said port.
 28. A gas compressor as claimed in claim 21, wherein said piston comprises an annular outer peripheral wall portion, an inner annular hub portion, and generally radially extending spokes interconnecting said portions.
 29. A gas compressor as claimed in claim 28, wherein said spokes are spaced inwardly from the planes of said opposite end surfaces of said piston. 